c. 77) was an Act of the Parliament of the United Kingdom which set limits on the practice of, and instituted a licensing system for animal experimentation, amending the Cruelty to Animals Act 1849.

The Act stipulated that researchers would be prosecuted for cruelty, unless they conformed to its provisions, which required that an experiment involving the infliction of pain upon animals to only be conducted when "the proposed experiments are absolutely necessary for the due instruction of the persons [so they may go on to use the instruction] to save or prolong human life".

This Act was created as a result, but was criticized by National Anti-Vivisection Society – itself founded in December 1875 – as "infamous but well-named," in that it made no provision for public accountability of licensing decisions.

The law remained in force for 110 years, until it was replaced by the Animals (Scientific Procedures) Act 1986,[4] which is the subject of similar criticism from the modern animal rights movement.

Such was the perceived weakness of the Act, that vivisection opponents chose, on at least one occasion – the Brown Dog affair – to incite a libel suit rather than seek a prosecution under the Act.